Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Numerator:
Net income attributable to Stewart (in $'000)	$ 16,964	$ 3,077
Denominator (in '000):
Basic average shares outstanding (in shares)	30,297	27,828
Diluted average shares outstanding (in shares)	30,809	28,341
Basic earnings per share attributable to Stewart (in usd per share)	$ 0.56	$ 0.11
Diluted earnings per share attributable to Stewart (in usd per share)	$ 0.55	$ 0.11
Stock options
Denominator (in '000):
Average number of dilutive shares relating to options and restricted units (in shares)	181	201
Restricted stock and restricted stock units
Denominator (in '000):
Average number of dilutive shares relating to options and restricted units (in shares)	331	312